Share-Based Compensation - Summary of Status of Company's Stock Option Plan (Detail) - Stock Option Plan - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares
Outstanding at beginning of period	2,633,589	3,280,874	2,517,911
-Cancelled		(132,500)
-Exercised	(589,725)	(679,291)	(292,537)
-Granted	1,170,534	164,506	1,055,500
Outstanding at end of period	3,214,398	2,633,589	3,280,874
Weighted Average Exercise Price
Outstanding at beginning of period	$ 2.06	$ 1.98	$ 1.33
-Cancelled		3.72
-Exercised	2.43	1.65	1.03
-Granted	3.95	3.28	3.28
Outstanding at end of period	$ 2.68	$ 2.06	$ 1.98